The present invention relates to a liquid filtration device of the type adapted to separate a liquid from solid particles, and is applicable notably to the filtration of a coffee infusion either in a household coffee machine or in a percolator.
Metal filters either in the form of perforated discs with or without raised edge, or in the form of a bell, are already known. Since the holes of these filters are extremely small, of the order of 0.15 to 0.2 mm, they clog inevitably. In this case, the only solution consists in clearing the hundreds of holes one by one with a pin.
In percolators pertaining to the pressure filter type filtration occurs under a certain pressure and the filter medium must have an adequate strength, and therefore a minimum thickness. To avoid any increment in the risk of clogging, it is known to flare the orifices out in the direction of flow. But also in this case the holes clog up rapidly as in thin filters.